Tooth filling and facing compositions comprising a radiopaque glass and method of making the same

ABSTRACT

A FILLER COMPOSITION FOR TOOTH FILLING AND FACING COMPOSITIONS COMPRISING (1) A FINELY DIVIDED INORGANIC MATERIAL, AND (2) A BARIUM ALUMINOSILICATE GLASS OR OTHER GLASS HAVING AN EFFECTIVE AMOUNT OF RADIOPAQUE OXIDE THAT RENDERS THE RESULTANT GLASS RADIOPAQUE TO X-RAYS USED BY DENTISTS. THE FILLER COMPOSITION IS MIXED WITH AN ORGANIC POLYMER SUCH AS METHYL METHACRYLATE TO PROVIDE A TOOTH FILLING AND FACING COMPOSITION HAVING AN OUTSTANDING COMBINATION OF DESIRABLE PROPERTIES INCLUDING A COLOR RESEMBLING THAT OF NATURAL TEETH, A SUITABLE INDEX OF REFRACTION, HARDNESS, WEAR RESISTANCE, A RELATIVELY LOW THERMAL EXPANSION MATCHING THAT OF NATURAL TEETH, AND BEING RADIOPAQUE TO X-RAYS USED BY DENTISTS.

y 3 74 E. D.'DIETZ 3,8 6 73 TOOTH FILLING AND FACING COMPOSITIONS COMPRISING A RADIOPAQUE GLASS AND METHOD OF MAKING THE SAME Original Filed Feb. -17, 1970 AVAVAVAVAYAVA I ygvvvAvAvA a AVVVAVAVAVAVAYA I 50 Avvvvmgvvvu AVAVAYAVAYAAVAYAVAVA 6o AVAYAVAVAVAVAYAVAVAVAVA 40 AYAYAYAVAVAYAVAYAYAYAVAYA 70 VAVAVAVAVAVAVAV,AYAVAVAVAVA 50 AVAVAVAVAVAVAV/IAYAYAYAVAVA f YAYAVA'auyvnlvnnn AVAVA!AYAVAYAVAVAVAYAVAVAVAVAVAVA AVAVAYAVAVAVAVAVAVAVAVAVAVAVAVAVAYA AVAVAVAVAVAVAVAVAVAVAYAVAVAYAVAYAVAVA 0 a .20 3a 40 JD a o y o fo o 3 United States Patent Office 3,826,778 Patented July 30, 1974 US. Cl. 260-4247 17 Claims ABSTRACT OF THE DISCLOSURE A filler composition for tooth filling and facing compositions comprising (1) a finely divided inorganic material, and (2) a barium aluminosilicate glass or other glass having an effective amount of radiopaque oxide that renders the resultant glass radiopaque to X-rays used by dentists. The filler composition is mixed with an organic polymer such as methyl methacrylate to provide a tooth filling and facing composition having an outstanding combination of desirable properties including a color resembling that of natural teeth, a suitable index of refraction, hardness, wear resistance, a relatively low thermal expansion matching that of natural teeth, and being radiopaque to X-rays used by dentists.

The present application is a divisional of application Ser. No. 12,109 filed Feb. 17, 1970.

THE INVENTION The present invention relates to a tooth filling and facing material having a combination of desirable properties including color resembling that of natural teeth, a compatible index of refraction, strength, hardness, a thermal coefiicient of expansion matching that of natural teeth, and being radiopaque to X-rays used by dentists. The invention particularly relates to a tooth filling and facing composition having a mixture of finely divided inorganic material and a radiopaque glass as a filler and an organic polymer as a binder.

In the past, there has been a problem in providing a suitable tooth filling and facing composition containing a filler composition and an organic polymer such as polymethyl methacrylate. The tooth filling and facing composition must have a combination of properties that includes a low coeflicient of thermal expansion to match that of natural teeth, strength, hardness, wear resistance, a color resembling that of natural teeth, and a compatible index of refraction While providing enough X-ray absorption to allow detection of the filled tooth. It has been difficult to provide a composition having all of the abovedescribed properties, particularly one that has a thermal coefficient of expansion to match that of natural teeth and still is radiopaque to X-rays used by dentists.

It is an object of the present invention to provide a composition for use as a filler in tooth filling and facing compositions in which the filler composition comprises (1) a finely divided inorganic material and (2) a glass having an effective amount of a radiopaque producing oxide that renders the resultant glass radiopaque to X-rays used by dentists, the .filler composition being capable of producing an outstanding tooth facing and filling material when mixed with an organic polymer, the resultant tooth repairing material having a combination of properties including a color resembling that of natural teeth, a suitable index of refraction, hardness, strength, wear resistance, a relatively low thermal expansion matching that of natural teeth, and being radiopaque to X-rays.

It is an object of the present invention to provide a filler composition for a tooth filling and facing composition and a method of making the filler composition and the tooth filling and facing composition.

These and other objects will be apparent from the specification that follows, the appended claims and the drawings in which:

The Figure is a ternary compositional diagram of BaOAl O -SiO glass systems showing suitable and preferred glasses that are radiopaque to X-rays used by dentists and are adapted for use as fillers in tooth filling and facing compositions.

The present invention provides a filler composition for use as a filler and tooth facing and filling composition comprising a finely divided inorganic material and a glass having an elfective amount of a radiopaque producing oxide that renders the resultant glass radiopaque to X-rays used by dentists. The resultant filler composition is incorporated in an organic binder such as an acrylic resin that produces a filling and facing composition that has a color resembling that of natural teeth, has a suitable index of refraction, has desired hardness and Wear resistance, has relatively low thermal expansion matching that of natural teeth, and is radiopaque to X-rays used by dentists.

It is preferred that the radiopaque glass filler be a barium aluminosilicate glass with a BaO content greater than about 22.5 percent by weight, such glass rendering the tooth filling and facing composition radiopaque to X-rays used by dentists. Furthermore, the resultant tooth filling and facing composition containing the barium aluminosilicate glass has a desirable color like that of natural teeth, a suitable index of refraction, high strength, wear resistance, a low thermal expansion matching that of natural teeth, and is nontoxic. Generally, the barium aluminosilicate glass is one consisting of BaO, A1 0 and SiO in the relative proportions by weight shown within the area marked by line I of the ternary diagram shown in the Figure. It is highly preferred that the radiopaque glass be one consisting essentially of BaO, A1 0 and SiO-,, in the relative proportions by weight shown inside the area marked by line II in the ternary diagram shown in the Figure. The optimum radiopaque glass is one consisting essentially of about 25-35 parts by weight of SiO;,, 10-20 parts by weight of A1 0 and 50-60 parts by Weight of BaO.

As previously indicated, a part of the filler composition is a finely divided inorganic material such as glass-ceramic material, quartz, fused silica, calcite, calcium carbonate, wollastonite, or other hard, finely divided inorganic filler having generally a mesh size of about 20 to 400 mesh, and preferably about to 200 mesh.

The filler composition which is inorganic material and the radiopaque glass is used in amounts of about 20-80 parts by weight with about 20-80 parts by weight of an organic polymer binder. The organic polymer is preferably an acrylic resin such as polyethyl methacrylate, polyethyl acrylate and polymethyl methacrylate and it is highly preferred that the resin be polymethyl methacrylate..

The acrylic polymer can be prepared from a monomer or mixtures of monomers having the general formula where R is an alkyl group of 1 to 3 carbon atoms and X is H or an alkyl group of 1 to 2 carbon atoms. The above acrylic monomers can be used in an amount of about 100 parts by weight with about 2 to 30 parts by weight of another copolymerizable monomer such as styrene, butadiene, ethylene and acrylic acid to provide a suitablepolymer for the tooth repairing compositions. Other polymers can be used such as polyvinyl chloride, cellulose acetate, and a styrene acrylonitrile copolymer providing the resultant composition is radiopaque, has the desired color, index of refraction, strength, wear resistance, thermal expansion and is nontoxic. The filler composition itself generally comprises about 50-90 parts by weight of the glass-ceramic material or other inorganic filler and about 10-50 parts by weight of radiopaque glass. Preferred amounts of the inorganic filler preferably having a low thermal coetficient of expansion are about 60-80 parts by weight to about 2040 parts by weight of the preferred barium aluminosilicate glass or other radiopaque glass. The optimum amounts are about 70-75 parts by weight of the inorganic material and about 25- 30 parts by weight of the glass. A highly preferred filler composition is one having about 70 parts by weight of a glass-ceramic consisting essentially of SiO Li O, Na O, K 0, CaO, Sb O A1 ZrO and TiO with about 30 parts by weight of a radiopaque glass having the following ingredients in approximate percent by weight:

Ingredient: Percent sio 25-35 A1 0 20 BaO 50 60 An especially useful glass-ceramic for obtaining the best balance of desired properties contains the following ingredients in approximate percent by weight:

An. especially useful radiopaque glass is one that contains the following ingredients in approximate percent by weight:

Ingredient: Percent SiO 26 A1 0 a 1 8 B 56 Although the preferred radiopaque producing oxide by far is barium oxide, it giving the best color and all around properties to the resultant composition, other radiopaque producing oxides such as strontium can be used. Also suitable but not as good as strontium oxide are lanthanum and other rare earth oxides of the lanthanide series, Nos. 57-71 such as samarium oxide, dysprosium oxide and terbium oxide can be used in which the mass absorption coefiicient of the element (including scattering) is generally above about 300 and preferably above about 350 for CllKa, 1.5418 A. The mass absorption coefiieient of Ba is given as 359 and lanthanum as 378. However, the lanthanum oxide generally imparts some undesirable color to the tooth filling and facing composition as does praseodymium oxide.

The following example illustrates the present invention.

EXAMPLE A series of filler compositions comprising parts by weight of a barium aluminosilicate glass mixed with 70 parts by weight of a glass-ceramic were prepared and the resultant filler compositions mixed in an amount of about parts by weight with 50 parts by weight of a liquid, solvent-soluble, further curable, methyl methacrylate polymer. The glass-ceramic used was one containing the following ingredients in approximate percent by weight:

Ingredient: Percent Si0 67 A1 0 20 T 0 1.7 ZI'OZ 2 Sb O .3 C210 3. Li O 4 Na O 0.4 K 0 0.2

The barium aluminosilicate glass used was one of the following series in which the ingredients are given in weight percent and mole percent.

Weight percent Mole percent 5102 A120 189.0 810; A1 0; BaO

The resultant mixture was used as a tooth facing and filling composition, the mixture being formed to the desired shape and the organic binder being cured by heating or at room temperature to thereby remove the solvent and form a thermoset polymer that binds the finely divided filler within its matrix.

The resultant compositions all had an outstanding combination of properties including a color resembling that of natural teeth, strength, wear resistance, abrasion resistance, a low thermal expansion matching that of natural teeth and were radiopaque to X-rays used by dentists. The mass absorption coefficients were calculated for copper Ka radiation which has a wavelength of about 1.5418 A. From the standpoint of glass processing including a desirable liquidus, compatible index of refraction and absorption coefficient, it is highly preferred that the radiopaque barium aluminosilicate glasses be ones having compositions similar to that of F and G in the above Table. Hence, the optimum glasses contain about 18-32 weight percent SiO 8-22 weight percent A1 0 and about 56-62 weight percent BaO. Glasses in the barium aluminosilicate system shown in the area bounded by line I of the Figure are advantageous because they have low coefficients of thermal expansion in the range of about 60 up to or X10- C. and have an index of refraction similar to that of natural teeth. The calculated X-ray absorption coefiicients of the barium aluminum silicate glasses shown in A through G, X and Y in the Table are as follows:

Mass Linear absorption absorption coefficient Density coelfieient The mass absorption coefiicients for the elements for CUKa, 1.5418 A, were taken from Appendix V, X-Ray Diffraction Procedures, H. P. Klug and L. E. Alexander, John Wiley & Sons, New York 1959.

As seen in the above Table, generally the linear absorption coefiicient can be as low as about 200 to 220 although it i; preferred that the coefficient be at least about 340 or 50.

As can be noted in an article 'by R. H. Thomas entitled Equilibrium In A Portion Of The Ternary System BaOAl O SiO Journal American Ceramic Society, Vol. 33, February 1950, pages 35-44, the liquidus temperatures of the glasses inside the area of line I are within the range of about 1300 C. to 1700 C. and hence are easily melted, processed and formed. The preferred compositions have a liquidus in the range of about 1400 to 1600 C.

What is claimed is:

1. A tooth facing and filling material comprising 20 to 80 parts by weight of a filler composition and 20 to 80 parts by weight of an organic polymer as a binder therefor, said parts by weight being based on the total weight of said facing and filling material; said filler composition comprising 50 to 90 parts by weight of a finely divided inorganic material and to 50 parts by weight of a barium aluminosilicate glass, said parts by weight being based on the total weight of said filler composition; said glass having a BaO content greater than about 22.5 percent by weight, and said organic polymer binder being at least one polymer selected from the group consisting of acrylic resin, polyvinyl chloride, cellulose acetate and styrene acrylonitrile copolymer, the facing and filling material being compatible with natural teeth, having a coefficient of thermal expansion matching that of natural teeth, having a color like that of natural teeth, being hard and wear resistant, having an index of refraction matching that of natural teeth, and being radiopaque to X-rays used by dentists.

2. A material as defined in claim 1 in which the organic polymer is at least one acrylic polymer selected from the group consisting of polyethyl methacrylate, polyethyl acrylate, and polymethyl methacrylate.

3. A material as defined in claim 1 in which the glass consists essentially of the following ingredients in approximate weight percentages:

4. A material as defined in claim 1 in which the particle size of said finely divided inorganic material is between about 20 and 400 mesh.

5. A material as defined in claim 4 in which the particle size of said finely divided inorganic material is between about 100 and 200 mesh.

6. A material as defined in claim 4 in which said finely divided inorganic material is selected from the group consisting of glass-ceramic material, quartz, fused silica, calcite, CaCO and wollastonite, having a low coefiicient of thermal expansion.

7. A material as defined in claim 6 in which said in- Organic material is a glass-ceramic material consisting essentially of SiO Li O, Na O, K 0, CaO, Sb O A1 0 21-02 and Tloz.

8. A material as defined in claim 1 in which the filler composition consists essentially of about 60 to 80 parts by weight of inorganic material and about 20 to 40 parts by weight of barium aluminosilicate.

9. A material as defined in claim 8 in which the filler composition consists essentially of about 70 to 75 parts by weight of inorganic material and about 20 to 30 parts by weight of barium aluminosilicate.

10. A material as defined in claim 1 in which the barium aluminosilicate glass consists essentially of BaO, A1 0 and SiO in the relative proportions by weight shown inside the area of line I shown in the ternary diagram of FIG. 1.

11. A material as defined in claim 10 in which the barium aluminosilicate glass consists essentially of BaO, A1 0 and SiO in the relative proportions by weight shown inside the area of line II shown in the ternary diagram of FIG. 1.

12. A material as defined in claim 1 in which the barium aluminosilicate glass consists essentially of about 25 to 35 percent by weight SiO about 10 to 20 percent by weight A1 0 and about 50 to 60 percent by weight BaO.

13. A material as defined in claim 1 in which the barium aluminosilicate glass consists essentially of 18 to 32 percent by weight SiO about 8 to 22 percent by weight A1 0 and about 56 to 62 percent by weight BaO.

14. A material as defined in claim 1 in which said barium aluminosilicate glass has a coefficient of thermal expansion in the range of about 55 10- C.

15. A material as defined in claim 1 in which said barium aluminosilicate glass has an X-ray linear absorption coefiicient between 223 and 626.

16. A material as defined in claim 1 in which said organic polymer is at least one acrylic polymer selected from the group consisting of polyethyl methacrylate, polyethyl acrylate and polymethyl methacrylate, said inorganic material is a glass-ceramic material having a particle size between about 20 and 400 mesh, and said barium aluminosilicate glass consists essentially of BaO, A1 0 and Si0 in the relative proportions by weight shown inside the area of line I shown in the ternary diagram of FIG. 1 and has a coefficient of thermal expansion in the range of about 55Xl0"/- C. to about X 10 C.

17. A material as defined in claim 1 wherein said organic polymer is a copolymer of an acrylic monomer and another copolymerizable monomer selected from the group consisting of styrene, butadiene, ethylene and acrylic acid.

References Cited UNITED STATES PATENTS 3,423,829 1/ 1969 Halpern et al. 10635 3,504,437 3/ 1970 Siegel 32-8 3,467,534 9/1969 MacDowell 106-39 3,390,456 7/1968 Deleva 32-15 2,877,199 3/1959 Taub l06--35 OTHER REFERENCES Phase Equilibrium in a Portion of the Ternary System 800-February 1950. Al O SiO by Thomas, Journal of the Am. Ceramic Society, vol. 33, pp. 35-44.

ALLAN LIEBERMAN, Primary Examiner J. H. DERRINGTON, Assistant Examiner US. Cl. X.R. 

